Embodiments of invention relates to power converters and more specifically to a multilevel converter.
In the last few decades, the field of power conversion has grown tremendously due to its imminent advantages in motor drives, renewable energy systems, high voltage direct current (HVDC) systems, and the like. The multilevel converter is emerging as a promising power conversion technology for various medium and high voltage applications.
Multilevel converters offer several advantages over an ordinary two-level converter. For example, the power quality of the multilevel converter is better than that of two level converters. Also, the multilevel converters are ideal for interface between a grid and renewable energy sources such as photovoltaics (PV), fuel cells, wind turbines, and the like. In addition, the efficiency of the multilevel converter is relatively higher as a result of its minimum switching frequency.
In the recent times, the multilevel converters having a modular structure and without transformers have been designed. The modular structure of the converters, allows stacking of these converters to an almost unlimited number of levels. Also, the modular structure aids in scaling up to different power and voltage levels. One example of such type of multilevel converters is a modular multilevel converters (MMC) which employees a large number of fully controllable semiconductor switches, such as insulated gate bipolar transistors (IGBTs).
Grounding is an important aspect of multilevel converters. A ground point or earth point refers to a node in the multilevel converter from which various node voltages are measured. Generally, the ground point determines voltage insulation ratings of various components in multilevel converter. Furthermore, the voltage insulation ratings are determined based on maximum voltage respect to search ground a particular component may observe during normal conditions and faults.